I’ve been pouring over medical journals, news articles, etc. trying to find an answer to what should be a simple question. Specifically, there are tons of articles that all say that the lifetime number of sexual partners is strongly linked to the risk of STD infection, but none of them will say how strongly.
In other words, I can’t find a study that provides statistics that show the relative risk increase for multiple partners compared to a base-line of no sexual partners. I’m looking for something like the risk table from the Varghese, Maher, Peterman, Branson, and Steketee study mentioned in this Straight Dope article. I.e. something that makes a comparison to the effect of:
People with a lifetime number of 1 sexual partner are X times more likely to contract an STD than those with 0.
People with a lifetime number of 2 sexual partners are Y times more likely to contract an STD than those with 0.
…
Basically, I’m having an argument with someone over the relative importance of condomn use compared to other sexual behavior factors. The Varghese, et al. study pretty effectively demonstrates that for any single sex act, the known/unknown HIV status of your partner is considerably more important than condomn use, as can be the nature of the act itself. But I’d still like to find statistics that relate overall risk of infection to the frequency of sexual activity and number of partners.
The question seems to get complciated very quickly because no one is sure of the relation (or not) between number of partners and other factors. That is, there’s no doubt that people who have a larger lifetime number of sexual partners are at a greater risk, but there are several things that could be attributed to. Maybe they’re also less like to use condoms or to use them correctly; maybe they tend to choose partners who also have sex with with multiple partners, thus increasing their exposure even more; no one seems to know for sure.
Basically what I want to know is if you remove the overlap, is promiscuity itself riskier than unprotected sex? Any thoughts, links, etc.?